Can you tell big armhole from the measurement?

[bluebonnet]

I was chatting with an online assistant for a blazer and was told that the 36S sized one has the armhole with a circumference 20.75 inches. Does that sound very big? And does it translate into low armhole?

If everything else is ok, can I buy it and ask for a tailor to make the alteration to reduce the armhole?

Thanks.

 

[landshark]

Armholes are near impossible to be made smaller. It would be incredibly difficult.